Abstract: Study 2 Screening and carefully individualized referrals are unlikely to reduce rates of suicide attempts or suicide mortality, partially because rates of follow through with referral are only ~25% among screen-positive youth identified in primary care. Furthermore, suicidal youth are less likely to follow through with outpatient mental health referrals, and drop out of treatment earlier and at greater rates than non-suicidal youth. As such, successful efforts to enhance follow through with referral for at-risk youth identified in primary care holds great promise in reversing the alarming trend of rising youth suicide rates. Research has identified common and potentially modifiable barriers that impede readiness to engage in mental health treatment in both at-risk youth and their parents. Assessing and targeting these individualized barriers may successfully motivate initiation and ongoing engagement with mental healthcare. We therefore propose to develop and test a behavioral theory-based, interactive text messaging (TM) intervention that targets barriers to engaging in mental health treatment for youth age 12-18 who are referred by their primary care provider for mental health treatment for depression. We will optimize the TM intervention effects by interacting with both youth and parents, tailoring materials to individuals based on depression symptoms and perceived barriers reported at baseline, and adapting the intervention over time based on reported progress. Resultant data will inform providers of outcomes based on their preferred mode of communication. We will first solicit stakeholder feedback on the intervention. We will then conduct an open treatment development case series in Year 1 to develop and iteratively refine the TM intervention. Resultant data will inform a small open pilot trial. Subsequently, we will conduct a randomized trial in Years 2-3 comparing the TM intervention with standard practice. The investigators have previous experience in building and testing interventions to improve medication adherence in pediatric bipolar patients and a texting intervention that was effective in reducing binge-drinking in young adults. Since there is evidence that increasing the receipt of mental health services for depressed individuals can reduce morbidity and mortality due to suicidal behavior, if this approach improves adherence, it can be an important tool to help reverse the upward trend in teen suicide. This approach is in direct accord with the aims of ALACRITY, prioritizing the rapid development, testing, and refinement of novel interventions involving technology to optimize treatment or prevention of mental disorders that are adapted to real world settings and are clinically and fiscally sustainable.